US3981978A - Working up aqueous titanium dioxide hydrate suspensions - Google Patents

Working up aqueous titanium dioxide hydrate suspensions Download PDF

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Publication number
US3981978A
US3981978A US05/577,492 US57749275A US3981978A US 3981978 A US3981978 A US 3981978A US 57749275 A US57749275 A US 57749275A US 3981978 A US3981978 A US 3981978A
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filter cake
titanium dioxide
bars
pressure
filter
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US05/577,492
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English (en)
Inventor
Raoul Weiler
Henri Uwents
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Bayer Antwerpen NV
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Bayer Antwerpen NV
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • C01G23/0475—Purification

Definitions

  • TiO 2 can be removed from ilmenite ores or titanium slags by disintegration with sulfuric acid. Hydrolysis of the titanyl sulfate formed yields titanium dioxide hydrate which is after separation from the mother liquid (diluted sulfuric acid) calcined and ground.
  • the titanium dioxide hydrate which accumulates during hydrolysis is in the form of very fine particles and, in addition, generally contains foreign substances in such quantities that it cannot be subjected to calcination without additional purification stages. Precipitated titanium dioxide hydrate is fairly difficult to filter on account of its compressibility and fine particle size.
  • the titanium dioxide hydrate which accumulates during hydrolysis from the sulfuric acid titanyl sulfate solution, which generally contains iron and other impurities, is normally separated from the diluted sulfuric acid with so-called Moore filters.
  • Moore filters are particularly suitable for slow filtration and operate under vacuum. They also enable the filter cake to be washed out. More information on Moore filters may be found, for example, in D. B. Purchas, Industrial Filtration of Liquids, Sec. Edition, Leonard Hill Books, pages 278 to 279.
  • FIGURE is a flow sheet of the process.
  • an iron-containing solution of titanyl sulfate in sulfuric acid is hydrolyzed at a temperature in the range from 80° to 120°C.
  • a first filtration stage 2 the formed titanium dioxide hydrate is separated from the diluted sulfuric acid on a Moore filter, after which the filter cake may be treated with washing water 3 on the filter.
  • the filter cake initially contains some 40 % by weight of iron (expressed as Fe 2 O 3 , based on solid TiO 2 ) and, where slag is used as the raw material, the filter cake contains some 25 % by weight of iron.
  • the iron content can be reduced to around 0.1 % by weight of iron by a washing process.
  • the cake After filtration and, optionally, washing, the cake is thrown off manually suspended in water and subjected to bleaching 4 (for example adding 5 aluminum and H 2 SO 4 at 80°C).
  • bleaching 4 for example adding 5 aluminum and H 2 SO 4 at 80°C.
  • the bleached suspension is refiltered on a Moore filter 6 and normally treated with washing water 7 until the iron content of the filter cake has fallen to less than 40 ppm of Fe 2 O 3 .
  • This filter cake is again thrown off manually and resuspended to form a slurry.
  • By adding different chemicals at 8 it is possible to make an adjustment 9 which will specifically influence the properties of the pigment in the calcining furnace.
  • the adjusted titanium dioxide hydrate suspension is then concentrated by means of a rotary drum filter 10 to a solid content of about 38 % by weight (based on TiO 2 ) and calcined in a calcination furnace 11 at about 600°C to 1200°C to form the TiO 2 clinker in anatase or rutile form.
  • the titanium dioxide hydrate can be separated on a Moore filter or a rotary drum filter and the filter cake can be treated on the filter with various washing liquids.
  • the iron content may be reduced to levels of 40 ppm and less by adding washing liquid containing titanium (III) ions. After suitable adjustment for calcination, the filter cake may then be directly introduced into the calcining furnace.
  • This object is realized by an improvement in the conventional recovery process in which such a suspension is subjected to at least one stage of filtration and washing to form a washed filter cake, the cake composition is adjusted and it is then calcined.
  • the filtration of the suspension is effected under a pressure of about 1 bar to 16 bars to form a homogeneous substantially crack-free filter cake of a thickness of about 10 to 25 mm.
  • a membrane filter for example of the type illustrated on page 225 and described on pages 223 and 227 of "Industrial Filtration of Liquids", D. B. Purchas, Sec. Edition, Leonard Hill Books, is particularly suitable for carrying out the process according to the invention.
  • a filter of this kind comprises horizontal filter compartments which enable filter cakes to be obtained in any layer thickness from 10 mm to 35 mm. Filtration may be carried out under pressures of from 1 to 16 bars and preferably under pressures of about 3 to 6 bars.
  • the filtration is combined with one or more washing stages and the filter cake is treated on the filter.
  • the filter cake may be washed under pressures from 1 to 16 bars and preferably under pressures of about 4 to 10 bars.
  • the filtration stages which are carried out using a Moore filter or rotary drum filter may also be carried out using a membrane filter.
  • two successive filtration stages or all the filtration stages which are necessary in the process illustrated in the flow sheet are combined into one stage.
  • the titanium dioxide hydrate hydrolysis sludge present in homogeneous and substantially crack-free form may be washed out by passing the washing liquids through the filter cake at flow rates of about 0.1 to 1 m/h and preferably at flow rates of about 0.3 to 0.7 m/h. Titanium (III) may be added to the washing water in concentrations of about 0.8 to 4 g of Ti 3 + /liter.
  • the iron content may readily be adjusted to levels below 25 ppm based on solid TiO 2 .
  • the process stage referred to as "adjustment" in the flow sheet may also be readily carried out on the filter.
  • the filter cake is prepared for calcination by adding the chemicals normally used in the adjustment.
  • the filtration output in the case of anatase amounted to between 120 and 130 kilograms per square meter per hour for a filter surface of 2.5 m 2 (based on TiO 2 ).
  • the filtration output was approximately 20 % lower in the case of rutile.
  • the solid content amounted to approximately 50 % by weight in the case of anatase and to 48.5 % by weight in the case of rutile.
  • the optimum filter cake thickness amounted to between 15 and 25 mm.
  • the filter cake was not compressed between the filtration and washing steps.
  • the filtration output in the case of anatase amounted to 44.2 kilograms per square meter and hour. It was about 20 % lower in the case of rutile.
  • the optimum cake thickness amounted to between 15 and 25 mm.
  • the cake has an Fe-content of 20 ppm and the same solid content as in Example 1.
  • the starting suspension had an iron content of 22 % by weight expressed as Fe 2 O 3 on solid TiO 2 .
  • the filtration cycle was carried out as follows:
  • a concentration of 1.6 g of Ti 3 + /liter was adjusted in the washing water.
  • the iron content of the filter cake after blowing dry amounted to 25 ppm based on solid TiO 2 and the solid content to 50 %.
  • the optimum cake thickness was between 15 and 25 mm.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Cosmetics (AREA)
  • Detergent Compositions (AREA)
  • Filtering Materials (AREA)
US05/577,492 1974-05-17 1975-05-14 Working up aqueous titanium dioxide hydrate suspensions Expired - Lifetime US3981978A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DT2423983 1974-05-17
DE2423983A DE2423983C3 (de) 1974-05-17 1974-05-17 Verfahren zum Aufbereiten wäßriger Titandioxidhydrat-Suspensionen durch Druckfiltration

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US3981978A true US3981978A (en) 1976-09-21

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US05/577,492 Expired - Lifetime US3981978A (en) 1974-05-17 1975-05-14 Working up aqueous titanium dioxide hydrate suspensions

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US (1) US3981978A (de)
JP (1) JPS50160198A (de)
BE (1) BE829189A (de)
BR (1) BR7503060A (de)
CA (1) CA1072885A (de)
CS (1) CS197246B2 (de)
DE (1) DE2423983C3 (de)
ES (1) ES437754A1 (de)
FI (1) FI751432A (de)
FR (1) FR2271174B1 (de)
GB (1) GB1489015A (de)
HU (1) HU171549B (de)
IT (1) IT1040591B (de)
NL (1) NL7505671A (de)
NO (1) NO140181C (de)
SU (1) SU841595A3 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4978396A (en) * 1989-05-12 1990-12-18 Kerr-Mcgee Chemical Corporation Process for preparing high solids slurries
US5174817A (en) * 1989-06-29 1992-12-29 Bayer Aktiengesellschaft Process for the calcination of filter cakes with high solids contents being partly pre-dried in a directly heated rotary kiln
WO1994011084A1 (de) * 1992-11-11 1994-05-26 BOKELA Ingenieurgesellschaft für mechanische Verfahrenstechnik mbH Verfahren zur mechanischen entfeuchtung eines filterkuchens und vorrichtung zur durchführung des verfahrens
US5352712A (en) * 1989-05-11 1994-10-04 Borden, Inc. Ultraviolet radiation-curable coatings for optical fibers
US5639846A (en) * 1989-05-11 1997-06-17 Borden, Inc. Ultraviolet radiation-curable coatings for optical fibers and optical fibers coated therewith
US6048505A (en) * 1997-06-16 2000-04-11 Kemicraft Overseas Limited Continuous non-polluting liquid phase titanium dioxide process and apparatus
US6409929B2 (en) 1992-11-11 2002-06-25 Bokela Ingenieurgesellschaft Fur Mechanische Verfahrenstechnik Mbh Steam drying of rotary filter cakes without crack formation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3938693C2 (de) * 1989-11-22 1993-12-02 Bayer Ag Verfahren zur Herstellung von TiO¶2¶-Pigmenten
DE19806471A1 (de) * 1998-02-17 1999-08-19 Kerr Mcgee Pigments Gmbh & Co Reines Titandioxidhydrat und Verfahren zu dessen Herstellung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2148283A (en) * 1936-05-11 1939-02-21 Nat Lead Co Preparation of white titanium dioxide pigments
FR1422120A (fr) 1964-09-21 1965-12-24 British Titan Products Procédé perfectionné de préparation d'oxyde de titane pigmentaire

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2148283A (en) * 1936-05-11 1939-02-21 Nat Lead Co Preparation of white titanium dioxide pigments
FR1422120A (fr) 1964-09-21 1965-12-24 British Titan Products Procédé perfectionné de préparation d'oxyde de titane pigmentaire

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"Hackh's Chemical Dictionary," by J. Grant, 4th Ed., 1969, p. 77, McGraw-Hill Book Co., N.Y. *
"Industrial Filtration of Liquids," 2nd Ed., 1971, pp. 278-279, by D. B. Purchas, Leonard Hill Books, London. *
"Titanium," J. Barksdale, 2nd Ed., 1966, pp. 317-323, The Ronald Press Co., N.Y. *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5352712A (en) * 1989-05-11 1994-10-04 Borden, Inc. Ultraviolet radiation-curable coatings for optical fibers
US5639846A (en) * 1989-05-11 1997-06-17 Borden, Inc. Ultraviolet radiation-curable coatings for optical fibers and optical fibers coated therewith
US4978396A (en) * 1989-05-12 1990-12-18 Kerr-Mcgee Chemical Corporation Process for preparing high solids slurries
US5174817A (en) * 1989-06-29 1992-12-29 Bayer Aktiengesellschaft Process for the calcination of filter cakes with high solids contents being partly pre-dried in a directly heated rotary kiln
WO1994011084A1 (de) * 1992-11-11 1994-05-26 BOKELA Ingenieurgesellschaft für mechanische Verfahrenstechnik mbH Verfahren zur mechanischen entfeuchtung eines filterkuchens und vorrichtung zur durchführung des verfahrens
US6409929B2 (en) 1992-11-11 2002-06-25 Bokela Ingenieurgesellschaft Fur Mechanische Verfahrenstechnik Mbh Steam drying of rotary filter cakes without crack formation
US6048505A (en) * 1997-06-16 2000-04-11 Kemicraft Overseas Limited Continuous non-polluting liquid phase titanium dioxide process and apparatus

Also Published As

Publication number Publication date
HU171549B (hu) 1978-02-28
NL7505671A (nl) 1975-11-19
FI751432A (de) 1975-11-18
SU841595A3 (ru) 1981-06-23
JPS50160198A (de) 1975-12-25
FR2271174B1 (de) 1980-08-22
DE2423983C3 (de) 1978-09-07
AU8104075A (en) 1976-11-18
IT1040591B (it) 1979-12-20
BR7503060A (pt) 1976-04-13
CS197246B2 (en) 1980-04-30
ES437754A1 (es) 1977-05-16
NO140181B (no) 1979-04-09
CA1072885A (en) 1980-03-04
GB1489015A (en) 1977-10-19
NO140181C (no) 1979-07-18
BE829189A (nl) 1975-11-17
NO751598L (de) 1975-11-18
FR2271174A1 (de) 1975-12-12
DE2423983A1 (de) 1975-12-04
DE2423983B2 (de) 1977-12-15

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